U.S. Pat. No. 1,985,111 to M. R. Shofer et al. disclosed a liner for shipping containers including a bottom, a pair of side walls, a pair of end walls, and four corner segments foldably forming a container for packing and shipping purposes. Each corner segment has a pair of tongues 26 so that the overlapped tongues 26 may be inserted into each slit 24 cut in the corner segment for assembling a rectangular container as shown in their FIG. 1 for lining, packing and shipping uses. However, each L-shaped slit 24 cut in the corner segment is positioned below an upper edge of each side wall 14, 15, whereby if such a container is served for filling liquid material in the container, the liquid material will be easily leaked outwardly through the slits 24, unless the filling level is below the slits 24. A lower filling level below the slits 24 will decrease the storing capacity or content within the container. It is therefore not suitable for providing the container of U.S. Pat. No. 1,985,111 as a container for filling liquid material in the container.